Method of and means for removing condensate from cooling elements of air-conditioning systems



May 15, 1951- L MCNEELY 2 53J43 METHOD OF AND MEANS FDR REMOVING CONDENSATE FROM COOL ELEMENTS OF AIR CONDITIONING SYSTEMS Filed May 20, 1947 ZMQZZ m? n ATTORN EY Patented May 15, 1951 UNITED STATES TENT OFFICE Lowell McNeely, Evansville, Ind, assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application May 20, 1947, Serial No. 749,303

4 Claims.

This invention relates to air conditioning and particularly to the cooling and dehumidification of air.

In air conditioning systems wherein a single cooling element is used for both cooling and dehumidifying air, it is often found that during low load operations, such as when the demand for cooling requires that only a relatively small amount of refrigerant be supplied to the cooling element, that the refrigerant is spent in passing through a part of the cooling element and that the remainder of the cooling element remains warm. This is particularly true with a vertically disposed cooling element wherein a volatile refrigerating medium is supplied to the upper part thereof for series flow downward therethrough, in which case, air passing over the upper or cold portion of the cooling element is cooled below its dew point and moisture removed from the air is condensed and deposited upon the upper part of the cooling element. This condensate drips or trickles from the upper part of the cooling element onto the lower or unrefrigerated portion thereof, whereupon the condensate is re-evaporated by Warm air passing over the lower or warm portion of the cooling element. The re-evaporation of the moisture on the warm portion of the cooling element is a direct loss of latent heat removal from the air. Furthermore, the reevaporation of such moisture causes the air to be cooled to a lower temperature than that required or desired.

It is, therefore, an object of this invention to provide, in an air conditioning system wherein a single cooling element is used to both cool and dehumidify air, means for disposing of any condensate that collects upon the upper portion of the cooling element to thereby prevent re-evaporation of such condensate on the lower portion of the cooling element during low load operations of the cooling system.

The above and other objects and advantages of my invention will be more clearly understood from the following detailed description and accompanying drawing, wherein the single figure is a view diagrammatically illustrating an air conditioning system embodying my invention.

Referring now to the drawing, the air conditioning system includes generally an air duct In in which is located a filter II, an evaporator or cooling element I2, a heating element I3, a humidifier I4, a blower I5, an inlet duct I6, and an outlet duct I! for delivering conditioned air to a room or enclosure I8 that is to be conditioned.

Any type of refrigerating system may be used for supplying a refrigerating medium to the evaporator or cooling element I2. However, I prefer a low-pressure absorption refrigerating system like that disclosed in United States Patent to Per Edberg, No. 2,368,455, granted January 30, 1945. The refrigerating system disclosed in this Edberg patent operates at a partial vacuum and contains a refrigerant-absorbent solution wherein water is the refrigerant and lithium chloride or lithium bromide or a suitable mixture of such salts is the absorbent. A system of this type includes a generator, a condenser, an evaporator, an absorber and conduits interconnecting such elements for flow of the refrigerating medium and the absorption solution. In operating such a system heat is applied to the generator whereby refrigerant vapor is expelled from solution, which vapor flows to the condenser wherein the vapor is condensed and the liquid refrigerant produced thereby flows into the evaporator. In the evaporator the refrigerant is vaporized by heat which may be picked up from an air stream passing over the exterior surface thereof. The vapor produced in the evaporator flows into the absorber wherein the vapor is absorbed by the absorption solution, and the enriched absorption solution is returned to the generator. Only so much of the refrigerating system as is necessary for a complete understanding of my invention is illustrated in the drawing. However, for a complete disclosure of the refrigerating system reference may be had to the above Edberg patent.

While not limited to, my invention is particularly useful with an evaporator of the type disclosed in the above Edberg patent. As shown, the evaporator I2 includes a plurality of substantially horizontal tubes I 9 provided with heat transfer fins 2i]. Refrigerant is supplied to the upper tubes of the evaporator from a condenser 2| through a conduit 2 I The refrigerant is distributed to the upper row of tubes and flows downward in series flow through the lower tubes. The means for supplying and distributing the refrigerant to the upper part of the evaporator is not a part of my invention and therefore need not be described in detail herein. However, as stated above, the evaporator may be of the type illustrated and described in the above Edberg patent, therefore, reference may be had to said patent for a detailed description of an evaporator and refrigerant distributing means that may be used with my invention.

When it is desired to cool and dehumidify the air in the enclosure I8, the air is drawn through 3 inlet duct l6, through the filter H, over the fins and tubes of the evaporator l2, over the heat radiator l3, and humidifier M by the blower l5, which air is returned to the enclosure through the duct 11. In passing over the cooling element the air is cooled below its dew point and moisture removed from the air condenses and collects upon the cooling element, which condensate may drip from one tube thereof onto the next lower tube. So long as the demands for cooling are great enough to cause refrigerant to be supplied to the cooling element in quantities such that the whole of the cooling element is supplied with refrigerant, all of the air passing over the cooling element is cooled and returned to the room or enclosure. However, on part load, such as half load, the refrigerant in passing through the upper portion of the cooling element is spent and when such refrigerant reaches the lower portion of the cooling element it produces substantially no refrigerating effect, .in which case condensate dripping from the upper to the lower portion of the cooling element will be re-evaporated by the relatively warm air passing over the lower portion of the cooling element. 7

In accordance with my invention, I provide a drip pan 22 located .substantially midway of the top and bottom of the cooling element 1-2. A drain pipe 23 delivers collected condensate from the drip pan 22 to a second drip pan 2 2, which latter pan is located directly beneath the lower portion of the cooling element. A second drain pipe 25-delivers condensate from drip pan 24 into a trough 26, and from the trough 25 the condensate is delivered by a conduit 27 into a collecting vessel 28, from whence the condensate may be disposed of in a suitable manner.

During low load operations the moisture that collects upon the tubes of the upper half of the cooling element is collected in the drip pan 22 and flows therefrom through conduit 23 into drip pan 24 without coming in contact with the tubes of the lower portion of the cooling element. During fullinput operations, that is, when sufiicient refrigerant is supplied to cool the entire cooling element, condensate that collects on the lower tubes thereof is caught by drip pan '24 and conveyed therefrom by drain pipe 25.

Refrigerant vapor formed in the evaporator tubes flows from the ends thereof into headers, not shown, and from the headers the refrigerant vapor flows into an absorber 29 wherein the vapor is absorbed in a suitable absorption medium such as lithium chloride or lithium bromide.

From the above it is seen that I have .provided a simple and inexpensive means .for collecting and disposing of moisture which condenses upon the upper portion of a cooling element at substantially the same temperature at which it is formed to thereby prevent such condensate from being re-evaporated upon the lower portion of the cooling element during low load operations ofthe cooling system.

When it is desired to heat the air in the enclosure IB, steam is supplied to the heating element l3 by a conduit 3il'from a suitable source, and water is supplied to the humidifier l4 'by a conduit 3| from a suitable source. A conduit 32 is provided for conveying overflow from 4 the humidifier l4 into a trough 33. From the trough, the overflow water is conveyed by a conduit 34 into the receptacle 28.

Having thus disclosed my invention, I wish it understood that I do not desire to be limited to the specific structure illustrated and described, for obvious modifications may occur to a person skilled in the art.

What is claimed is:

1. An air cooling system comprising an air duct, a cooling element within said air duct, means for supplying a refrigerating medium to an upper portion of the cooling element for series flow downward therethrough, and means positioned intermediate an upper and lower portion of said cooling element for removing any condensate that forms upon the upper'portion of said cooling element at substantially the same temperature at which it is formed.

2. An air cooling system comprising an air duct, a cooling element within said air duct, means for supplying a refrigerating medium to an upper portion of the cooling element for series flow downward therethrough, and means including a drain pan positioned intermediate an upper and lower portion of said cooling element for causin parallel flow of air over the upper and lower portions of the cooling element and for removing any condensate that forms upon the upper portion of said cooling element at substantially the same temperature at which it is formed.

3. The method of cooling and dehumidifying air which comprises passing a stream of air over a single cooling element, dividing said stream of air into a plurality of streams for parallel flow over said cooling element, refrigerating a certain portion only of said cooling element, whereby only a certain portion of said divided air stream will be cooled, and diverting any moisture which condenses out of the cooled portion of said air stream from contact with the remaining or uncooled portion thereof, whereby the evaporation of said moisture is prevented.

4. The method of cooling and dehumidifying air which comprises passing a substantially horizontal stream of air over a single cooling element, dividing said stream of air into upper and lower portions for parallel flow over said cooling element, cooling only the upper portion of said air stream below its dew point, and diverting any moisture which condenses out of that portion of the air stream which is cooled below its dew point from contact with that portion of the air stream that is not cooled below its dew point.

LOWELL MCNEELY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

